Search results

The purpose of this investigation was to develop a digital instrument for the quantitative evaluation of pitting corrosion in metals.

This investigation comprised two central parts: research, testing and monitoring of the formation of pitting by conventional methods and applying American Society for Testing and Materials (ASTM) Standards, and the development of a virtual instrument based on the LabVIEW 2010 platform.

The methodology used was suitable for the analysis of pitting on carbon steel and aluminum alloy UNS A96061, used in the aerospace industry.

This technique allows pits to be to localized, measured and quantified on metallic surfaces, for corrosion evaluation in atmospheric and industrial environments.

This combination of conventional and digital methods can assist in corrosion control of pitting in industrial equipment.

Colonies of Actynomyces israelii bacteria have been found in removed copper intra‐uterine devices (IUD) used as a long‐term contraceptive method. The purpose of this paper is to characterize the biofilm developed under anaerobic conditions by Actynomyces israelii on IUD surface, and its influence in the copper corrosion processes.

The dissolution of copper on the intra‐uterine cavity prevents conception because of the toxic effect of the ions released. Nevertheless, microbiological growths have been detected on the IUD devices retired after long periods of insertion. In order to know about the influence of the biofilm on the corrosion of copper, electrochemical, spectroscopic and surface analysis techniques were applied to study the phenomenon.

A porous Actynomyces israelii biofilm was formed on the copper IUD surface. The bacteria colony had developed in an exopolimeric substrate, which protects it from the toxic effect of copper ions. The corrosion process was not inhibited by the biofilm, due to the pores present which permit the transport of species through them.

The results of this study show that there is no decay in the contraceptive function of the IUDs due to the presence of a bacterial biofilm on its surface.

The relationship between microbial colonization and the corrosion process of copper IUD under anaerobic conditions was characterized. These results will complement previous investigations performed on the study of corrosion of copper IUDs under different conditions.

The purpose of this paper is to evaluate the corrosion of silver due to hydrogen sulphide pollutant in indoor conditions at a microelectronics plant located in Mexicali, Baja California, a semi‐arid zone in the northwest of Mexico.

Silver coupons and silver plated on to copper‐lead frames are exposed in the assembly process building of a microelectronics company during a period of 60 days and also in a sheltered test chamber that simulates indoor conditions with ambient concentrations of atmospheric pollutants, temperature and relative humidity (rH). Other exposures are made in the test chamber to study the corrosion behaviour of silver coupons over a duration of 24 months. The corrosion products were analysed using the Scanning Electron Microscope (SEM) and Energy Dispersive X‐ray Spectroscopy (EDS). Corrosion rates were measured by Quartz Crystal Microbalance (QCM) under laboratory‐controlled conditions.

The presence of silver sulphide corrosion products, dendrites and whiskers is observed on the exposed samples using SEM and EDS analysis.

The paper is designed to establish whether the company, where the exposure is taking place, constituted an indoor environment with outdoor hydrogen sulphide pollutant in sufficient concentration to induce silver corrosion.

The methodology used in this work can be applied to study the indoor corrosion behaviour of other metals, which will be of interest to the microelectronics industry.

The purpose of this paper is to evaluate the hygienic design of a scalable unit for supercritical carbon dioxide drying of food.

For the purpose of this study, a checklist has been developed, covering requirements from sanitary standards and industry-tailored guidelines. Beyond hygienic design, failure mode and effects analysis of the results were performed to assess the potential food safety risks that may arise from failures to hygienic design requirements.

The overall score of the hygienic design was 46 percent. This kind of evaluation revealed two types of nonconformities. The first type was related to inadequate sanitary procedures. The second type was associated to design failures.

The highest risk was designated to problems related to cleaning and sanitation followed by risks associated with the formation of dead zones and biofilms.

This study provides valuable insight to engineers and food technologists on hygienic design issues.

Application of a similar methodology was used for evaluating hygienic design of other non-thermal food technologies.

The purpose of this paper is to report a study of microbiological influenced corrosion (MIC) of copper due to bacteria strains isolated from potable water pipes and oxidation lagoons using electrochemical noise (EN) analysis and scanning electron microscopy (SEM).

Bacteria strains isolated from copper surfaces of potable water pipes and from oxidation lagoons were identified, based on the 16S rDNA gene sequence analysis. Corrosion studies were undertaken over a period of six weeks, placing copper electrodes inside an LB culture media with and without bacteria. The corrosion resistance was obtained using EN analysis. In all the cases, the corrosion type was identified. SEM images of the copper electrodes were taken to evaluate the surface condition.

The bacteria strains identified were: Pantoea agglomerans, Alcaligenes faecalis, Bacillus cereus, Brucellaceae bacterium, Enterobacter cloacae, Delftia tsuruhatensis, and Pseudochrobactrum asaccharolyticum. EN analysis gave noise resistance values in the range 1,036‐5,040 Ωcm² for the control samples and in the range of 2,336‐22,573 Ωcm² for samples that had been inoculated with bacteria. It was found that a decrease in the rate of corrosion took place due to the development of a biofilm by the microorganisms on the copper surface. SEM images corroborated the presence of the biofilm on the copper electrodes.

The isolated bacteria strain reduced the rate of corrosion on the copper electrodes, as shown by the SEM images and EN analysis results, due to the formation of a biofilm that can act as an anticorrosive coating.

Even though MIC is a known phenomenon, it has not been reported that isolated bacteria strains can reduce corrosion on the surface of copper potable water pipes and in oxidation lagoons.

The purpose of this paper is to study the immobilization of porcine pancreatic lipase (PPL), in an organic matrix by a covalent cross-linking method to sense propylparaben (PP) present in aqueous solution.

PPL immobilization was performed by the covalent cross-linking method, using bovine serum albumin (BSA) in the presence of saturated glutaraldehyde vapor (GA). The preparation of the enzymatic membrane involves the incorporation of porcine pancreatic lipase (PPL), bovine serum albumin (BSA) and glycerol into a phosphate buffer solution (PBS). Characterization of this sensor was performed by impedance spectroscopy (EIS) and scanning electron microscope (SEM). The effect of experimental conditions such as PPL activity, potential, scan rate, PP concentration, pH and presence of interfering elements were studied by cyclic voltammetry.

Under the optimal experimental conditions, a number of significant factors were optimized. The method exhibited good linearity in the range of 10^–14 to 10^–9 mol/L with a good correlation coefficient of 0.957, detection limit (LOD) of 3.66 × 10^–15 mol/L and high sensitivity of 1.086 mA mol⁻¹L. The authors also obtained a very good coverage rate of the surface equal to 91.44%, and hydrolytic activity of lipase is evaluated to 26.64 mmol min⁻¹. The stability and the interference were also evaluated. The equivalent circuit used to explain the electrochemical behavior of modified electrode is a Randle circuit.

The main application of biosensors is the detection of biomolecules that are either indicators of a disease. For example, electrochemical biosensing techniques can be used as clinical tools to detect breast tumors, because these compounds (PP) were found in breast tumors.

The result registered in this paper indicates that the developed sensor is an efficient, fast, simple and inexpensive analytical tool that can be used for the analysis of water containing PP.

This paper aims to study the effect of different processing treatments to reduce cypermethrin residues in okra and judge the consumer preferences of the applied unit operations. Deliberate use of pesticides on vegetables has been frequently reported in recent past. Association of pesticides with multiple health odds in human beings necessitates its removal from diet.

Cypermethrin residues were analysed using Quick Easy Cheap Effective Rugged Safe method and quantified using gas chromatography. Consumer acceptability was judged using a 9-point Hedonic scale.

Significant reductions were observed in all treatments applied. Percentage reduction observed with different pre-treatments ranged from 36 per cent (tap water) to 89 per cent (acetic acid and potassium permanganate). All cooking methods, except microwave cooking, were found effective, as the per cent reduction varied from 91 to 98 per cent. Maximum reductions were observed with pressure cooking. However, on the basis of organoleptic scores, washing was the most preferred pre-treatment, followed by sodium bicarbonate. Least score was obtained by samples treated with potassium permanganate. Among the cooking methods, all samples were acceptable, except pressure cooking. Taking into consideration both factors, i.e. residue reduction and consumer acceptability, sodium bicarbonate, sodium chloride and frying were found to be the best household treatments.

Present study pioneered and tried to establish links between the efficacies of laboratory to the consumer level, thereby judging its utility. Further research must focus on taking this parameter of food safety to real applied research at the consumer level.

This paper aims to focus the synchronous chemical conversion technology–based titanium/zirconium composite on 6061, 7075 aluminum alloys and galvanized steel.

The effects of pH, temperature, reaction time and other process parameters on the corrosion resistance of the three metal surface coatings were investigated by copper sulfate drop and electrochemical corrosion performance tests under a certain content of H2TiF6 and H2ZrF6. The surface morphology and element distribution of the conversion coating were analyzed by scanning electron microscope and X-ray photoelectron spectroscopy.

The results show that the optimal synchronization chemical conversion conditions of 6061/7075 aluminum alloys/galvanized steel are controlled as follows: H2TiF6 2.2 mL/L, H2ZrF6 1 mL/L, pH 3.9, conversion temperature 35°C and conversion time 120 s.

Multi-metals chemical conversion coating can be obtained simultaneously with uniform corrosion resistance and surface morphology. The presence of microdomain features in multiple metals facilitates simultaneous chemical conversion into coatings.

This paper aims to illustrate the main contributions of the context-gender discussion in entrepreneurship research and its main developments over time to identify promising future research avenues.

This paper builds on the author’s extensive knowledge of the context-gender debate and on several recent overviews and reviews of the debate. It is written as essay, introducing its main themes through a personal reflection and complemented by a selective review of research on gendered contexts and women’s entrepreneurship.

The context-gender discussion has moved forward. The first wave of context-gender studies contextualized gender, considering the impact of contexts on women’s entrepreneurship. Nowadays, studies are conducted on how contexts are gendered and how they are constructed in gendered ways through, for example, words, images, cognitions, as well as how women entrepreneurs can impact on and enact their contexts.

This paper contributes novel insights into contextualizing gender and gendering contexts. It is unique in suggesting that a perspective on gendering contexts will allow to explore the diversity of entrepreneurship and further develop theories related to contexts and gender.

The German government only recently started paying attention to the topic of female entrepreneurship as an important means to raise the overall level of entrepreneurship. Most relevant support policies concentrate on extending and stabilising the financial base of new female‐owned ventures. Relevant consultancy appears to play a less important role, although there has been a shift towards integrated packages in recent years. However, access to mainstream support is implicitly gender biased. Moreover, an integrated strategy for fostering female entrepreneurship also needs to consider that there are shortcomings in the institutional (political and societal) environment, possibly restricting women's interest in entrepreneurship and thus determining the extent of female entrepreneurship.